Free fatty acid metabolism in Chinese hamsters.

Abstract

In normal Chinese hamsters (Cricetulus griseus) the mean concentration of free fatty acids (FFA) in serum varied from group to group, but was (i) consistently 4 to 9 times greater than in rats, dogs, or man; (ii) slightly higher than in Syrian hamsters; (iii) two- to four-fold higher than in fasting or alloxan-diabetic rats. The epididymal adipose tissue of the Chinese hamster (i) had initial concentrations of FFA comparable to those in the rat and Syrian hamster; (ii) released, in the same time interval, 8- to 10-fold more FFA in vitro than this tissue of the rat; (iii) had higher concentrations of FFA after incubation than the incubated tissue of the rat. The retroperitoneal (perirenal) adipose tissue of the Chinese hamster was less active in release of fatty acids in vitro than the epididymal, but was, however, more active than the epididymal adipose tissue of the rat. These characteristics of FFA metabolism in the Chinese hamster were apparently attributable to species, not to age, diet, or sex. In the Chinese hamster, the weight of the epididymal adipose tissue per gram of body was relatively high. It appears that in this species the rate of release of fatty acids from adipose tissue is great, leading to high FFA concentrations in serum.In Chinese hamster and rat adipose tissues in vitro, glucose and insulin (separately) reduced the rate of release of FFA and the amount of FFA in the tissues, but glucose and insulin together produced the greatest reductions. The net reduction in FFA release by glucose and insulin in vitro was greater in tissue from the Chinese hamster. Insulin markedly increased glucose uptake by the adipose tissues of both species. The possible relation of the results to spontaneous diabetes in the Chinese hamster is discussed.